title: Influence of adhesive techniques on fracture resistance of endodontically treated premolars with various residual wall thicknesses.
abstract: BACKGROUND
  The choice of restorative method is commonly based on the cavity configuration and the residual number of cavity walls. However, the residual wall thickness could be a valuable clinical parameter in the choice of restoration for endodontically treated teeth.
  
  
  OBJECTIVE
  The fracture resistance of endodontically treated premolars was compared with different wall thicknesses restored with direct composite resin with and without cuspal coverage and with and without fiber post insertion.
  
  
  METHODS
  This study included 104 intact human maxillary premolars extracted for periodontal or orthodontic reasons. Standardized mesio-occluso-distal cavities were prepared with different palatal wall thicknesses (1.5, 2, and 2.5 mm) and a buccal wall thickness of 2 mm. Teeth were restored with or without a fiber post and with or without cuspal coverage. Specimens were subjected to thermocycling (3000 cycles, 5 to 55°C) and embedded in polymerized acrylic resin. Teeth were submitted to cyclic fatigue followed by a static fatigue test with a universal testing machine; a compressive force was applied 30 degrees to the long axis of the teeth until fracture. The results were statistically analyzed by 3-way ANOVA (α=.05).
  
  
  RESULTS
  Residual wall thickness (P=.004), the type of adhesive restoration (P<.001), and fiber post insertion (P<.001) significantly influenced the fracture resistance of endodontically treated premolars.
  
  
  CONCLUSIONS
  In specimens with a cavity wall thickness >2 mm, direct intracuspal composite resin restorations supported by a fiber post achieved comparable fracture resistance. With a residual wall thickness <2 mm, only cuspal coverage with or without a fiber post provided satisfactory fracture resistance.
authors.affiliation: Assistant Professor, Department of Cariology and Operative Dentistry, Dental School Lingotto, University of Turin, Turin, Italy. Electronic address: nicola.scotti@unito.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Scotti
authors.forename: Riccardo
authors.initials: R
authors.lastname: Rota
authors.forename: Marco
authors.initials: M
authors.lastname: Scansetti
authors.forename: Davide Salvatore
authors.initials: DS
authors.lastname: Paolino
authors.forename: Giorgio
authors.initials: G
authors.lastname: Chiandussi
authors.forename: Damiano
authors.initials: D
authors.lastname: Pasqualini
authors.forename: Elio
authors.initials: E
authors.lastname: Berutti
mesh_terms: D001641:Bicuspid / Q000473:pathology*; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003737:Dental Cavity Preparation / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D011176:Post and Core Technique / Q000295:instrumentation; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D019228:Tooth Crown / Q000473:pathology*; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*
chemical_list: D003188:Composite Resins; D003764:Dental Materials